共查询到20条相似文献,搜索用时 15 毫秒
1.
V. G. Slutskii E. S. Severin L. A. Polenov 《Russian Journal of Physical Chemistry B, Focus on Physics》2007,1(6):549-552
The H3BO3 ? HBO2 + H2O, HBO2 + HBO2 ? (HBO2 · HBO2) complex, and (HBO2 · HBO2) ? B2O3 + H2O reactions of forward and reverse conversion of H3BO3 into B2O3 and the (HBO2 · HBO2) ? (HBO2)2 reactions of forward and reverse transformation of the complex into a fairly stable dimer (HBO2)2 were studied ab initio at the MP2/6-31+G*//6-31+G* level. The transition state method and calculated equilibrium constants were used to determine forward and reverse reaction constants. 相似文献
2.
3.
Electronically nonadiabatic effects during the chemisorption of hydrogen atoms on an Al(111) surface are simulated ab initio using time-dependent density-functional theory for the electrons in combination with Ehrenfest dynamics for the nuclei. Strongly nonadiabatic effects close to the spin transition of the H atom are identified, and the dissipated energy as well as the electron-hole pair excitation spectra are calculated. The recent Newns-Anderson-model approach by Mizielinski et al. is confirmed. The simulations illustrate the physical processes that contribute to internal exoelectron emission. 相似文献
4.
5.
M. Zemzemi S. Alaya Z. Ben Ayadi 《Journal of Experimental and Theoretical Physics》2014,118(6):945-950
Solar cells based on transparent conductive oxides such as ZnO/Cu2O constitute a very advanced way to build high-performance cells. In this work, we are interested in the characterization of the interface through nanoscale modeling based on ab initio approaches (density functional theory, local density approximation, and pseudopotential). This work aims to build a supercell containing a heterojunction ZnO/Cu2O and study the structural properties and the discontinuity of the valence band (band offset) from a semiconducting to another phase. We build a zinc oxide in the wurtzite structure along [0001] on which we place the copper oxide in the hexagonal (CdI2-type) structure. We choose the method of Van de Walle and Martin to calculate the energy offset. This approach fits well the density functional theory. Our calculation of the band offset gives a value that corresponds to other experimental and theoretical values. 相似文献
6.
Ab initio study of graphene on SiC 总被引:1,自引:0,他引:1
Employing density-functional calculations we study single and double graphene layers on Si- and C-terminated 1x1-6H-SiC surfaces. We show that, in contrast with earlier assumptions, the first carbon layer is covalently bonded to the substrate and cannot be responsible for the graphene-type electronic spectrum observed experimentally. The characteristic spectrum of freestanding graphene appears with the second carbon layer, which exhibits a weak van der Waals bonding to the underlying structure. For Si-terminated substrate, the interface is metallic, whereas on C face it is semiconducting or semimetallic for single or double graphene coverage, respectively. 相似文献
7.
8.
S. N. Al-Refaie 《Applied Physics A: Materials Science & Processing》1992,55(2):213-217
The volume density of trapping states is derived throughout the metal-dielectric interface. This has been facilitated by equating the dielectric loss component to the tunneling conductance using a new relaxation time formulation. Subsequently, the trap distribution at the Al/InPO4 interface has featured a peak of 1.15×1019 cm–3 at about 15 Å from the Al contacting electrode. The new approach could be extended to deal with semiconductor-dielectric interfaces. 相似文献
9.
10.
11.
采用从头计算B3LYP,MP3和MP4方法结合Aug-cc-pVDZ基组研究了CH3C(O)OSSOC(O)CH3最稳定的五种构象及其阳离子构型.理论计算了五种稳定构象的转动常数和偶极矩;运用电子传播子理论P3近似方法计算稳定构象外价壳层轨道的电离能,计算结果与光电子能谱实验结果符合的较好.根据构象的相对能量以及理论模拟电离能谱和实验光电子能谱之间的比较,说明在气相光电子能谱实验中至少存在两种构象.与中性构型相比,电离后的五种阳离子构型均发生了明显的结构弛豫,尤
关键词:
构象
电离能
相对能量
光电子能谱 相似文献
12.
13.
Ab initio methods have been used to investigate the properties of Pd as impurity in bulk SiC at five charged states within the framework of density functional theory using the local spin density approximation. It was found that Pd interstitials and substitutionals have similar energy to their intrinsic counterparts. In addition, Pd substitutes for a vacancy, di-vacancy, and tri-vacancy with similar energies. Pd diffuses through SiC via an interstitial mechanism employing the tetrahedral sites and Pd can substitute for Si and C at positive charged states. Removing electrons (p-type doping) from SiC lowers the formation and migration energies of Pd defects in SiC for most configurations. 相似文献
14.
In this work, a first-principles study on PrAg compound using the density functional theory implemented in the projector-augmented wave (PAW) method in the CsCl (B2) crystal structure has been performed. Based on the optimized structural parameter, which is in good agreement with experimental data, the electronic structure, elastic, thermodynamics and vibrational properties have been investigated. The temperature and pressure variations of volume, bulk modulus, thermal expansion coefficient, heat capacities, and Debye temperatures in wide pressure (0-30 GPa) and temperature ranges have also been predicted. 相似文献
15.
《Surface science》1998,418(1):64-70
We present first-principles total-energy calculations of (001) surfaces of SrTiO3. Both SrO-terminated and TiO2-terminated surfaces are considered, and the results are compared with previous calculations for BaTiO3 surfaces. The major differences are in the details of the relaxed surface structures. Our calculations argue against the existence of a large ferroelectric relaxation in the surface layer, as had been previously proposed. We do find some indications of a weak surface ferroelectric instability, but so weak as to be easily destroyed by thermal fluctuations, except perhaps at quite low temperatures. We also compute surface relaxation energies and surface electronic band structures, obtaining results that are generally similar to those for BaTiO3. 相似文献
16.
17.
Ab initio configuration interaction calculations are performed to study the chemisorption of atomic H on a Fe(110) surface. The lattice is modeled as an embedded three-layer, 40-atom cluster with the Fe atoms fixed at the bulk position. Fe 3d orbitals are explicitly included on five Fe atoms on the surface. Hydrogen strongly binds to the Fe(110) surface at the long-bridge, short-bridge, and quasi three-fold sites. The calculated adsorption energies are 2.76, 2.73, and 2.71 eV, respectively. H-surface bonding at the on-top Fe site is more than 0.4 eV weaker. The calculated H-surface distances are 0.89, 1.03, and 0.87 Å for H at the long-bridge, short-bridge, and quasi three-fold sites, respectively, which agrees well with the LEED value of 0.9 ± 0.1 Å. The H-surface stretching vibrational frequencies are calculated to be 1070, 1066, and 1073 cm−1, at the long-bridge, short-bridge, and quasi three-fold sites, respectively. The work function of Fe(110) decreases on H adsorption. The present calculations indicate that H diffusion into the bulk through the short-bridge site will have a much higher activation barrier than via the long-bridge and quasi three-fold sites. 相似文献
18.
19.
为了研究Mg ,Al掺杂对锂二次电池正极材料LiCoO2 体系的电子结构的影响 ,进而揭示Mg掺杂的LiCoO2 具有高电导率的机理 ,对Li(Co ,Al)O2 和Li(Co,Mg)O2 进行了基于密度泛函理论的第一原理研究 .通过对能带及态密度的分析 ,发现在Mg掺杂后价带出现电子态空穴 ,提高了电导 ,并且通过歧化效应 (disproportionation)改变了Co 3d电子在各能级的分布 ,而Al掺杂则没有这些作用 .O2 - 的离子性在掺杂后明显增强 . 相似文献
20.
为了研究Mg, Al掺杂对锂二次电池正极材料LiCoO2体系的电子结构的影响,进而揭示Mg掺杂的LiCoO2具有高电导率的机理,对Li(Co, Al)O2和Li(Co, Mg)O2进行了基于密度泛函理论的第一原理研究. 通过对能带及态密度的分析,发现在Mg掺杂后价带出现电子态空穴,提高了电导,并且通过歧化效应(disproportionation)改变了Co-3d电子在各能级的分布,而Al掺杂则没有这些作用. O关键词:
2')" href="#">LiCoO2
电子结构
第一原理
电导 相似文献